This proposal focuses on the application of allylsilane cyclizations to form medium-sized rings. Novel and expendient syntheses of confertin and neolemnane exploit advantages unique to this annulation strategy. In addition, new methodology has been proposed to further develop this annulation procedure. The cyclization of substrates possessing several Michael acceptors, or internal nucleophiles, is a powerful extension of our earlier studies. Several pilot studies directed toward the ring skeletons of gascardic acid, gibberellic acid, quadrone, ophiobolin A, taxol, dendrobine, and securinine have been presented to expand the scope of our ring-forming processes. The area of allylsilane carbocyclizations remains largely unexplored and has significant potential. Pursuit of the experiments proposed here will further demonstrate the capabilities of this annulation methodology.